ZyCoV-D : India’s first and the world’s first DNA based covid vaccine

The Drug Controller General of India on 20th August gave approval to  Zydus Cadilla for Emergency Use Authorization for its covid vaccine ZyCoV-D, touted to be the world’s first and India’s first covid 19 vaccine which based on DNA and can be administered to all humans above 12 years of age.

The world’s first plasmid covid vaccine India’s second indigenous vaccine after Covaxin had earlier received recommendation by the Subjects Expert Committee (SEC) of the Central Drugs Standard Control Organization (CDSCO) which cleared a major hurdle in the vaccines’s emergency use.

Safety and efficacy

In the adaptive PhaseI/II clinical trials the ZyCoV—D demonstrated a robust immunogenicity and tolerance and safety profile said Zydus. The interim analysis of the symptomatic RT-PCR cases showed that ZyCoV-d had an efficacy of 66.6 percent for the three doses (2mg per dose).

No severe cases of Covid or deaths due to covid were found due to Covid-19 after the second dose was successfully administered said Zydus. After successfully administering the third dose no moderate case of covid-19 was observed in the covid arm implicating an efficacy of 100 percent in moderate cases.

If a rash appear after administering the vaccine then it s called a covid arm. More than 28000 volunteers volunteered to have phase -III trials conducted on them in more than 50clinical sites scattered across the country that too during the peak of the second wave of covid-19 in India which reassures the vaccine’s effectiveness against the new Delta variant – the new and the most dangerous strain of covid-19. Another big breakthrough of the company is that ZyCoV-D is safe for children that belong in the age group of 12-18 years. 

Needle-less vaccine

Another breakthrough of this vaccine is that it is needle-less and is transferres via an applicator called PharmaJet to ensure painless intradermal vaccine delivery. PharmaJet was also developed in India and in a record time.

Capacity

Zydus said it can produce 10-15 million doses of ZyCoV-D per month. The company said it can produce 3-5 crore vaccines by December. The capacity numbers suggest that Covishield and, to some extent, Covaxin will remain as the major workhorses for the government’s vaccination drive for some more time.

Evaluating two-dose regimen

Zydus said it has also submitted data for a two-dose regimen for ZyCoV-D, using a 3 mg dose per visit and the immunogenicity results had been found to be equivalent to the current three-dose regimen. The company said this would help in reducing the full-course duration of vaccination while maintaining a high safety profile in the future.

Children & adolescents

Zydus has submitted applications for EUA for children in the 12-18 year age group.

Novel approach

Zydus Cadilla has taken a novel approach for its potential COVID-19 vaccine. Called plasmid DNA, the vaccine consists of genetic material of SARS-CoV-2 proteins, which instruct human cells to make the SARS-CoV2 antigen, eliciting an immune response.

The company says that this approach is easily replicable and scalable, requiring just Biosafety Level (BSL)-1. The vaccine can be stored at 2-8 degrees temperature, making it conducive for Indian cold-chain conditions. The vaccine is delivered through the intradermal route (between the layers of the skin), which makes its administration much easier. DNA vaccines are also theoretically easy to redesign quickly against a mutating virus.

Challenges

Firstly, the platform is novel. Not a single human vaccine using this platform has been approved anywhere in the world. The other big challenge is that the vaccine has to be administered in three doses – the first dose, and the other doses after 28 and 56 days. Being a three-dose vaccine adds an additional layer of distribution and administration complexity, possibly raising the cost of the vaccine. While the company has promised to ensure that the vaccine is affordable, it has also sought approval for a two-dose vaccine.